Move response file handling to a separate package

sbox is going to need to read and write response files, move ReadRspFile
to its own package.

Test: response_test.go
Change-Id: Iecb5486b4aaeb2531828743ad8ef784df675e18e
diff --git a/zip/zip.go b/zip/zip.go
index 088ed0d..a6490d4 100644
--- a/zip/zip.go
+++ b/zip/zip.go
@@ -29,7 +29,8 @@
 	"sync"
 	"syscall"
 	"time"
-	"unicode"
+
+	"android/soong/response"
 
 	"github.com/google/blueprint/pathtools"
 
@@ -164,14 +165,12 @@
 	}
 	defer f.Close()
 
-	list, err := ioutil.ReadAll(f)
+	arg := b.state
+	arg.SourceFiles, err = response.ReadRspFile(f)
 	if err != nil {
 		b.err = err
 		return b
 	}
-
-	arg := b.state
-	arg.SourceFiles = ReadRespFile(list)
 	for i := range arg.SourceFiles {
 		arg.SourceFiles[i] = pathtools.MatchEscape(arg.SourceFiles[i])
 	}
@@ -253,49 +252,6 @@
 	Filesystem pathtools.FileSystem
 }
 
-const NOQUOTE = '\x00'
-
-func ReadRespFile(bytes []byte) []string {
-	var args []string
-	var arg []rune
-
-	isEscaping := false
-	quotingStart := NOQUOTE
-	for _, c := range string(bytes) {
-		switch {
-		case isEscaping:
-			if quotingStart == '"' {
-				if !(c == '"' || c == '\\') {
-					// '\"' or '\\' will be escaped under double quoting.
-					arg = append(arg, '\\')
-				}
-			}
-			arg = append(arg, c)
-			isEscaping = false
-		case c == '\\' && quotingStart != '\'':
-			isEscaping = true
-		case quotingStart == NOQUOTE && (c == '\'' || c == '"'):
-			quotingStart = c
-		case quotingStart != NOQUOTE && c == quotingStart:
-			quotingStart = NOQUOTE
-		case quotingStart == NOQUOTE && unicode.IsSpace(c):
-			// Current character is a space outside quotes
-			if len(arg) != 0 {
-				args = append(args, string(arg))
-			}
-			arg = arg[:0]
-		default:
-			arg = append(arg, c)
-		}
-	}
-
-	if len(arg) != 0 {
-		args = append(args, string(arg))
-	}
-
-	return args
-}
-
 func zipTo(args ZipArgs, w io.Writer) error {
 	if args.EmulateJar {
 		args.AddDirectoryEntriesToZip = true